Honda Tuning shares an office with the staffs of Turbo, European Car, Car Audio & Electronics, Import Tuner, and, until recently, Sport Compact Car. When you have this many car geeks in one room together, day in and day out, you can expect friendly competition to arise every once in a while.
A few months ago, I found myself picking at the remnants of a bowl of pho' while arguing the limitations of a D-series motor with Import Tuner's Technical Editor, Scott Tsuneishi. While Scott drives a WRX now, his roots are with Hondas, and he still has a few DA Integra project cars in his stable.
Like a lot of Honda guys, especially ex-Honda guys, Mr. Tsuneishi sees the D16 as a cute little brother to God's (Honda's) gift to the world, the B-series. When the subject of a 400+ wheel hp, turbocharged D16 came up, Scott chuckled with condescending disbelief when I told him that not only could I build it, but that I would. This sounded like a challenge to me, so I set out to build the biggest, most powerful D16Z6 I knew how. That'll show 'em.
In this month's installment, we start the build by modifying the cylinder head. Ricky Ortiz from Industrial Flow in Carson, Calif., ported our head and got it ready for a full Skunk2 top end treatment. Skunk2's .5mm oversized valves, valve springs, titanium retainers, stage-one camshaft, cam gear, and intake manifold have been employed to aid in our effort. With a top end like this, combined with a stout bottom end and a sufficient turbo setup, we will easily meet our 400 wheel hp goal.
When building a completely custom motor, the top end is the only place to start. Before we can design our custom pistons, we need to know the final volume of the head's combustion chambers. We also need to know the specs on the valvetrain combination we'll be using. These two parameters define what the piston crown will look like by helping us find our ideal compression ratio and valve relief configuration respectively. Once the head is done, the pistons can be made and the snowball keeps rolling downhill from there.
The five major parts of a complete top end job are: the surface, combustion chambers, cold side, hot side, and the valve job. Each one of these is important in it's own right and should all be taken into consideration when building a cylinder head.
SurfaceThe deck surface is the area of the cylinder head that mates with the bottom end. Since single cam Honda heads do not have very much meat on the deck surface, Ricky informs us that he will usually only take off what is necessary from the surface to leave a flat, precise mating area for the deck. While it is common practice in the aftermarket world to mill heads to gain compression, the inherent timing, heat transfer, and durability problems in doing so lead us to believe that this process should be left to the domestic guys from which the practice originated. A custom set of pistons and modified combustion chambers negate the need for milling anyway. Stick to resurfacing, you won't be sorry.